Identified the most efficient trajectories for inter-planetary travel.

Baron Guido von Pirquet, an Austrian pioneer of astronautics, was born in Hirschstetten Castle near Vienna on March 30, 1880. The son of a distinguished family, he studied mechanical engineering at the Technische Hochscules (Technical Institutes) in both Vienna and in Graz.

In 1926, von Pirquet served as chairman of the Technical Testing Committee of the Austrian Society of Inventors. That year, he and Franz von Hoefft founded the "Scientific Society for High Altitude Research,"the first space-related group in Europe, with von Pirquet as its first secretary. He began his pioneering work in rocketry and astronautics by building and testing rocket models in 1927, in a wind tunnel. His expertise in ballistics and thermodynamics helped make him a leading figure in early twentieth-century European rocketry.

Von Pirquet became well known for his ideas on the exploration of space in his 1928 book The Possibility of Space Travel, and in a series articles that appeared in 1929, in The Rocket, the journal of the VfR (the German Rocket Society), the worlds largest such club at the time. In these writings he described the most fuel-efficient trajectories for reaching the planets Venus, Mars, Jupiter, and Saturn. His trajectory for a space probe to Venus was identical to the one use by the first Soviet interplanetary spacecraft, Venera 1, launched to the planet Venus in February 1961.

Von Pirquet also proposed development of a space program through a three-phased evolution of rockets; first sounding rockets, then long distance rockets, and finally, rockets capable of reaching outer space, which is exactly how rocketry was to develop around the world.

Baron von Pirquet was also one of the earliest advocates of permanent, manned space stations. He proposed building three types of these -- the first in near-Earth orbit for weather and earth observation, the second in a 200-minute Earth-orbit as a platform for interplanetary flight, and a third station in an elliptical orbit shuttling between the first two. Von Pirquet believed orbital assembly for lunar and interplanetary spacecraft would be necessary as he felt rockets large enough to reach the planets would be too massive to lift off from the surface of the Earth.

The Nazi occupation of Austria in 1938, ended von Pirquet's interest in rocketry and space exploration. Baron Guido von Pirquet died at his ancestral home, Hirschstetten Castle, on April 17, 1966, at the age of eighty-six. A lunar crater is named for him.